In late 2004, on a visit to her son's grave, Alvina Carrington was surprised to find fresh flowers. 'I knew I hadn't put them there, so I thought it was odd,' she recalls. But Alvina assumed a friend or member of her family had brought them, and was touched someone had made the journey to Alperton cemetery on the north-west fringes of London to remember Luke, who had been stillborn at seven months.

After his death in October 2003 Alvina's life fell apart. She had lost the first child she desperately wanted and had spent six years trying for. An appalling series of blunders by doctors and midwives meant her pre-eclampsia went unidentified, with fatal consequences. Amid the shock, grief and anger, her relationship broke up. Previously very sociable, the 33-year-old became introverted and virtually housebound. She gave up her job, unable to stop crying every night after she got home. Alvina thought she had reached the lowest point of her life.

But more than a year after that trip to the cemetery, in early 2006, she suffered another heartbreak. In the course of asking what sort of headstone she could put on Luke's grave, Alvina discovered that what she thought was her son's final resting place also contained the bodies of several other babies. The flowers were for one of them, not Luke.

'I'd rung the cemetery, told them Luke was buried there, given them the plot number and asked them what size of headstone I could erect. I'd decided that I was going to have gold lettering saying "Blue: in our hearts always", because that was the nickname I'd given him, and then 'Luke' underneath.

'That would have been the final act. But the cemetery people explained to me that it wasn't my property, that it belonged to Brent Council, that I'd need to get their permission for the headstone and that there were other babies in the grave,' says Alvina. 'I was devastated. I thought it was Luke's grave and only Luke's grave, and that it was my property. I thought the cemetery had got it wrong. But they said to me: "It should have been explained to you that the grave belongs to the council and that other babies are there."

'I wanted to know how many other babies were in there beside Luke, and whether they were on top of each other or side by side. I wanted to know if there was another baby on top of Luke.'

Controversy surrounds what led to Luke's interment in a communal grave that is a public plot. It is undisputed that Northwick Park hospital, whose sub-standard care led to Luke's death - Alvina was paid £50,000 in compensation - made the funeral arrangements. They say they told Alvina exactly what sort of grave Luke would be laid to rest in and that their chaplain, who dealt with this delicate and little-known area of hospitals' work, was 'meticulous' in such matters.

Luke's mother vehemently disputes that. 'No one from the hospital told me anything about it being a shared grave or a plot that the council owned, and none of the correspondence or literature they sent me mentioned it,' she maintains. 'If I'd known I would never have agreed and would have arranged a private funeral instead.'

Northwick Park declined to answer questions from The Observer, citing patient confidentiality. But in earlier correspondence with Alvina's lawyer, Stephanie Prior of London firm Charles Russell, they confirmed that: 'Luke is buried in a public adult plot in the Brent cemetery of Alperton which has been divided into four quadrants. He is in a separate grave which is identifiable and a memorial can be erected.' That letter said that the hospital chaplain, with whom Alvina, her sister Janice and ex-partner discussed the plans for Luke's funeral, was 'meticulous about informing families about the fact that any burial arranged by the hospital would be in a public plot because if a parent is deeply religious they may object to a baby being buried next to a baby of a different religious faith'.

Crucially, the letter also included a copy of three documents which families who have had a child die before, during or shortly after birth at Northwick Park, receive. The first was the hospital's 'Care in pregnancy loss, baby and child death' policy paper. The others were an information leaflet called 'Easing the sorrow' and a pro forma letter that such parents usually receive. The letter states that the leaflet 'would have been given to the family' and that the letter 'would have been forwarded to Ms Carrington'.

But both Alvina and her sister are adamant they received neither. Stephanie Prior said last night: 'It appears that the hospital did not follow the appropriate guidelines regarding funeral arrangements in this instance. Alvina is adamant they were not told by the hospital chaplain that her deceased baby was going to be buried in a public plot at the cemetery. It was only almost two and a half years later, during the course of negotiations in her civil claim against the NHS Trust, that Alvina learned her baby was in a public grave with three other babies.

Hospitals across the country offer to make burial arrangements when a baby dies at birth. With 17 such cases in the UK every day, around 6,200 sets of parents a year may be given the choice of this service.

'This is a time of great sadness and trauma for the parents,' says Erica Stewart of Sands, the only national charity that helps parents who have lost a baby at birth. 'For some people it's too much for them, too overwhelming, to organise the funeral themselves after perhaps delivering a dead baby, seeing, holding and dressing it, and saying goodbye.'

Some hospitals use individual plots but others offer only shared graves. The national guidelines, which Sands produce and say most hospitals follow, are clear that: 'If their baby will be buried in a shared grave, parents should be told this in advance. They should be told how many babies will be in the grave. Parents should be given an estimate of how long it is likely to be before the grave is closed and the ground properly reinstated.' Alvina insists Northwick Park told her none of that.

Nearly two years on from Alvina's grim discovery Luke is still in plot NN52 in Alperton cemetery. There is no plaque giving the name of any of the four children inside. Cemetery regulations forbid any of the families from erecting a headstone due to restrictions of space. Alvina now finds herself in a second legal wrangle with Northwick Park over how her son ended up in plot NN52. She wants to have Luke exhumed and reburied, but Home Office permission is required when such a process involves a shared grave.

Alvina hopes hers is the only example of a parent learning the controversial truth about their baby's final resting place, but suspects it is not. 'I feel they treated Luke and me like dirt over the burial arrangements,' she says angrily. 'It may sound horrible to some people but hospitals should explain everything as that way there'll be no surprises later.'

'Let the parents know'

Guidelines set out how UK hospitals should care for grieving parents. 'Pregnancy Loss and the Death of a Baby', produced by Sands, the charity which helps those who have lost a baby through miscarriage, stillbirth or complications during labour, states:

· All parents should be offered written information relevant to the stage at which the pregnancy ended or the baby died, outlining what choices they have if they want the hospital to make the arrangements.

· Staff need to listen carefully and try to help parents make choices that reflect their own wishes and values.

· Staff who talk with parents should have a thorough understanding of the available options for babies of different gestations, and should know what is possible at local cemeteries and crematoria.

· If their baby will be buried in a shared grave, parents should be told this in advance. They should be told how many babies will be in the grave.